网络编程及三大协议（TCP + UDP + Http）

一、网络编程

1.计算机网络

是指将地理位置不同的具有独立功能的多台计算机及其外部设备，通过通信线路连接起来，在网络操作系统，网络管理软件及网络通信协议的管理和协调下，实现资源共享和信息传递的计算机系统。

2.网络编程

实现多台计算机之间实现数据的共享和传递，网络应用程序主要组成为：

网络编程+IO流+多线程

3.网络编程三要素

网络通讯的模型：请求-响应，客户端-服务端

三要素：IP地址，端口，协议（数据传输的规则）

1.IP地址

1.1.IP地址：网络中计算机的唯一标识（IP地址是一个32位的二进制数据，为了方便，将一个字节的二进制转换为一个十进制的数据）

1.2.IP地址的组成：网络号段+主机段

1.3.1.A类IP地址:第一段号码为网络号码，剩下的三段号码为本地计算机的号码

----可以配置256256256台主机

1.3.2.B类IP地址:前二段号码为网络号码，剩下的二段号码为本地计算机的号码

1.3.3.C类IP地址:前三段号码为网络号码，剩下的一段号码为本地计算机的号码

1.3.4.特殊地址:

127.0.0.1 回环地址,可用于测试本机的网络是否有问题. ping 127.0.0.1

DOS命令 ipconfig:查看本机IP地址

补充：

A类地址的表示范围为：0.0.0.0~126.255.255.255，默认网络屏蔽为：255.0.0.0；A类地址分配给规模特别大的网络使用。A类网络用第一组数字表示网络本身的地址，后面三组数字作为连接于网络上的主机的地址。分配给具有大量主机（直接个人用户）而局域网络个数较少的大型网络。例如IBM公司的网络。

B类地址的表示范围为：128.0.0.0~191.255.255.255，默认网络屏蔽为：255.255.0.0；

C类地址的表示范围为：192.0.0.0~223.255.255.255，默认网络屏蔽为：255.255.255.0；C类地址分配给小型网络，如一般的局域网和校园网，它可连接的主机数量是最少的，采用把所属的用户分为若干的网段进行管理。

2.端口号

正在运行的程序的标识

A:每个网络程序都会至少有一个逻辑端口

B:用于标识进程的逻辑地址，不同进程的标识不同

C:有效端口：0-65535，其中0-1024系统使用或保留端口。

a) 80

b) ftp:23

c) :80

通过第三方工具可以查看

注意：端口与协议有关：TCP和UDP的端口互不相干，同一个协议的端口不能重复，不同协议的可以重复

TCP:10086

UDP:10086

3.协议

通信规则，就是数据的传输规则

TCP、UDP都是传输层的协议

TCP建立连接，形成传输数据的通道；在连接中进行大数据量传输；通过三次握手完成连接，是可靠协议；必须建立连接，效率会稍低，例如：打电话

UDP将数据源和目的封装到数据包中，不需要建立连接；每个数据报的大小在限制在64k；因无连接，是不可靠协议；不需要建立连接，速度快：例如发短信

4.InetAddress – 主机类

import .InetAddress;import .UnknownHostException;public class Test01 {public static void main(String[] args) throws UnknownHostException {//获取到指定域名的服务器IP地址//InetAddress byName = InetAddress.getByName("");// System.out.println(byName);//14.215.177.39//获取到指定域名的所有服务器 IPd地址//InetAddress[] allByName = InetAddress.getAllByName("");//for (InetAddress inetAddress : allByName) {//System.out.println(inetAddress);//}//获取到本机的IP地址InetAddress localHost = InetAddress.getLocalHost();System.out.println(localHost);}}

二、TCP协议

Scoket也叫套接字，其表示的是IP地址和端口号的组合。

网络编程主要就是指Socket编程，网络间的通信其实就是Socket间的通信，数据就通过IO流在两个Scoket间进行传递。

import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.PrintStream;import .Socket;import .UnknownHostException;//客户端public class Client {//注意：关闭流等于关闭Socketpublic static void main(String[] args) throws UnknownHostException, IOException {//武松Socket socket = new Socket("127.0.0.001", 8888);//1.向服务端发送消息PrintStream ps = new PrintStream(socket.getOutputStream());ps.println("武松：小二，上好酒好菜！");//4.接收来自服务端的消息BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream(), "GBK"));String readLine = br.readLine();System.out.println(readLine);//关闭资源ps.close();br.close();socket.close();}}

import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.PrintStream;import .ServerSocket;import .Socket;//服务端public class Server {public static void main(String[] args) throws IOException {//客栈掌柜ServerSocket server = new ServerSocket(8888);System.out.println("等待端连接中...");//店小二//accept()是线程阻塞的方法，客户端和服务端连接成功后才会生成一个Socket对象Socket socket = server.accept();System.out.println("欢迎光临，客人来了~~~");//2.接收来自客户端的消息BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream(),"GBK"));String readLine = br.readLine();System.out.println(readLine);//3.向客户端发送消息PrintStream ps = new PrintStream(socket.getOutputStream());ps.println("店小二：好的，您请坐！");//关闭资源br.close();ps.close();socket.close();server.close();}}

1.TCP案例之 传输文件

import java.io.FileInputStream;import java.io.IOException;import java.io.OutputStream;import .Socket;import .UnknownHostException;public class Client {public static void main(String[] args) throws UnknownHostException, IOException {Socket socket = new Socket("127.0.0.002", 6666);//客户端读取源文件，通过Socket提供的输出流向服务端传输数据即可FileInputStream fis = new FileInputStream("测试视频.mp4");OutputStream os = socket.getOutputStream();byte[] b = new byte[1024];int len;while ((len = fis.read(b)) != -1) {os.write(b, 0, len);}fis.close();os.close();socket.close();}}

import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import .ServerSocket;import .Socket;public class Server {public static void main(String[] args) throws IOException {ServerSocket server = new ServerSocket(6666);Socket socket = server.accept();//通过Socket提供过的输入流接收来自客户端的数据，并写入到本地文件中InputStream is = socket.getInputStream();FileOutputStream fos = new FileOutputStream("copy.mp4");byte[] b = new byte[1024];int len;while ((len = is.read(b)) != -1) {fos.write(b, 0, len);}is.close();fos.close();socket.close();server.close();}}

2.TCP协议 之 一对一聊天

import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.PrintStream;import .Socket;import .UnknownHostException;import java.util.Scanner;public class Client {public static void main(String[] args) throws UnknownHostException, IOException {Socket socket = new Socket("127.0.0.001", 5555);Scanner scan = new Scanner(System.in);PrintStream ps = new PrintStream(socket.getOutputStream());BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream(),"GBK"));while (true) {ps.println("小小：" + scan.next());String readLine = br.readLine();System.out.println(readLine);}}}

3.TCP协议 之 优化一对一聊天

import java.io.IOException;import java.io.PrintStream;import .Socket;import .UnknownHostException;import java.util.Scanner;public class Client {public static void main(String[] args) throws UnknownHostException, IOException {Socket socket = new Socket("127.0.0.1",5010);new ReceiveThread(socket).start();Scanner scan = new Scanner(System.in);PrintStream ps = new PrintStream(socket.getOutputStream());while (true) {ps.println("刘备：" + scan.next());}}}

import java.io.IOException;import java.io.PrintStream;import .ServerSocket;import .Socket;import java.util.Scanner;public class Server {public static void main(String[] args) throws IOException {ServerSocket server = new ServerSocket(5010);Socket socket = server.accept();new ReceiveThread(socket).start();Scanner scan = new Scanner(System.in);PrintStream ps = new PrintStream(socket.getOutputStream());while (true) {ps.println("张飞：" + scan.next());}}}

import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import .Socket;public class ReceiveThread extends Thread{private Socket socket;public ReceiveThread(Socket socket) {this.socket = socket;}@Overridepublic void run() {try {BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream(), "GBK"));while (true) {String readLine = br.readLine();System.out.println(readLine);}} catch (IOException e) {e.printStackTrace();}}}

4.TCP协议 之 群聊

import java.io.IOException;import java.io.PrintStream;import .Socket;import .UnknownHostException;import java.util.Scanner;public class Client {public static void main(String[] args) throws UnknownHostException, IOException {Socket socket = new Socket("127.0.0.1", 4563);new ReceiveThread(socket).start();Scanner scan = new Scanner(System.in);PrintStream ps = new PrintStream(socket.getOutputStream());while (true) {ps.println("关羽：" + scan.next());}}}

import java.io.IOException;import .ServerSocket;import .Socket;import java.util.concurrent.ConcurrentHashMap;public class Server {public static final ConcurrentHashMap<String, Socket> map = new ConcurrentHashMap<>();public static void main(String[] args) throws IOException {ServerSocket server = new ServerSocket(4563);while (true) {Socket socket = server.accept();//获取客户端的IP地址String ip = socket.getInetAddress().toString();System.out.println(ip);//将IP地址和Socket对象存入Map中map.put(ip,socket);//此线程 -- 接收当前Socket的消息，并发送给其他Socketnew ServerThread(socket).start();}}}

import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import .Socket;public class ReceiveThread extends Thread{private Socket socket;public ReceiveThread(Socket socket) {this.socket = socket;}@Overridepublic void run() {try {BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream(),"GBK"));while (true) {String readLine = br.readLine();System.out.println(readLine);}} catch (IOException e) {e.printStackTrace();}}}

import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.PrintStream;import java.io.UnsupportedEncodingException;import .Socket;import java.util.Map.Entry;import java.util.Set;import java.util.concurrent.ConcurrentHashMap;public class ServerThread extends Thread{private Socket socket;public ServerThread(Socket socket) {this.socket = socket;}@Overridepublic void run() {//接收当前Socket的消息，并发送给其他Sockettry {BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream(),"GBK"));while (true) {String readLine = br.readLine();System.out.println(readLine);ConcurrentHashMap<String, Socket> map = Server.map;Set<Entry<String,Socket>> entrySet = map.entrySet();for (Entry<String, Socket> entry : entrySet) {String ip = entry.getKey();Socket value = entry.getValue();if (!socket.getInetAddress().toString().equals(ip)) {PrintStream ps = new PrintStream(value.getOutputStream());ps.println(readLine);}}}} catch (UnsupportedEncodingException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}}}

四、UDP协议

1.简介

UDP（User Datagram Protocol）用户数据报包协议，UDP和TCP位于同一层-传输层，但它对于数据包的顺序错误或重发没有TCP可靠；UDP是一种面向无连接的通信协议。UDP向应用程序提供一种发送封装的原始IP数据报的方法，并且发送时无需建立连接，不保证可靠数据的传输

UDP — 发短信

TCP — 打电话

import .DatagramSocket;import .SocketException;public class Client01 {public static void main(String[] args) throws SocketException {DatagramSocket socket = new DatagramSocket(8808);new ReceiveThread(socket).start();new SendThread(socket, "127.0.0.1", 9099, "马超").start();}}

import .DatagramSocket;import .SocketException;public class Client02 {public static void main(String[] args) throws SocketException {DatagramSocket socket = new DatagramSocket(9099);new ReceiveThread(socket).start();new SendThread(socket, "127.0.0.1", 8808, "吕布").start();}}

import java.io.IOException;import .DatagramPacket;import .DatagramSocket;public class ReceiveThread extends Thread{private DatagramSocket socket;public ReceiveThread(DatagramSocket socket) {this.socket = socket;}@Overridepublic void run() {while (true) {try {//数据容器byte[] buf = new byte[1024];//数据报包DatagramPacket dp = new DatagramPacket(buf, 0, buf.length);//接收数据报包socket.receive(dp);//打印System.out.println(new String(buf).trim());} catch (IOException e) {e.printStackTrace();}}}}

import java.io.IOException;import .DatagramPacket;import .DatagramSocket;import .UnknownHostException;import java.util.Scanner;public class SendThread extends Thread{private DatagramSocket socket;private String ip;private int port;private String name;public SendThread(DatagramSocket socket, String ip, int port, String name) {this.socket = socket;this.ip = ip;this.port = port;this.name = name;}@Overridepublic void run() {Scanner scan = new Scanner(System.in);while (true) {try {//数据byte[] buf = (name + ":" + scan.next()).getBytes();//数据报包DatagramPacket dp = new DatagramPacket(buf, 0, buf.length);//发送数据报包socket.send(dp);} catch (UnknownHostException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}}}}

2.TCP VS UDP

五、Http协议

1.Http案例之获取来电归属地

import java.io.IOException;import java.io.InputStreamReader;import .URL;import .ssl.HttpsURLConnection;public class Test01 {public static void main(String[] args) throws IOException {//获取链接地址URL url = new URL("https://cx./phonearea.php?number=15879090133");//获取连接对象HttpsURLConnection huc = (HttpsURLConnection) url.openConnection();//设置参数//设置请求方式huc.setRequestMethod("GET");//允许使用输入流huc.setDoInput(true);//允许使用输出流huc.setDoOutput(true);//设置连接超时时间huc.setConnectTimeout(5000);//设置读取超时时间huc.setReadTimeout(5200);//获取响应状态码int responseCode = huc.getResponseCode();if (responseCode == HttpsURLConnection.HTTP_OK) {//响应成功InputStreamReader isr = new InputStreamReader(huc.getInputStream(), "UTF-8");char[] c = new char[1024];int len;while ((len = isr.read(c)) != -1) {System.out.println(new String(c, 0, len));}isr.close();}else if(responseCode == HttpsURLConnection.HTTP_NOT_FOUND){System.out.println("报错了 --- 页面未找到");}}}

2.Http案例之获取快递

import java.io.IOException;import java.io.InputStreamReader;import .URL;import .ssl.HttpsURLConnection;public class test02 {public static void main(String[] args) throws IOException {//获取地址URL url = new URL("/?type=zhongtong&postid=78624759493002");//获取连接对象HttpsURLConnection huc = (HttpsURLConnection) url.openConnection();//设置参数//设置请求方式huc.setRequestMethod("GET");//允许使用输入流huc.setDoInput(true);//允许使用输出流huc.setDoOutput(true);//设置连接超时时间huc.setConnectTimeout(5200);//设置读取超时时间huc.setReadTimeout(5000);//获取响应状态码int responseCode = huc.getResponseCode();if (responseCode == HttpsURLConnection.HTTP_OK) {//响应成功InputStreamReader isr = new InputStreamReader(huc.getInputStream(),"UTF-8");char[] c = new char[1024];int len;while ((len = isr.read(c)) != -1) {System.out.println(new String(c, 0, len));}isr.close();} else if(responseCode == HttpsURLConnection.HTTP_NOT_FOUND){System.out.println("报错了 --- 页面未找到");}}}

3.Http案例之下载图片

import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import .URL;import .ssl.HttpsURLConnection;public class Test03 {public static void main(String[] args) throws IOException {//获取连接地址URL url = new URL("./th/id/R-C.f27d775447d9f4ab7c71bbe5f8e38831?rik=4ISLL%2fsQWoSY8g&riu=http%3a%2f%%2fphoto%2f40014%2f9369.jpg_wh860.jpg&ehk=S%2bDyu%2bhUKhk%2foLxQ6D7fO350Z%2fkmlDrRz5sM5J1QrCk%3d&risl=&pid=ImgRaw&r=0");//获取连接对象HttpsURLConnection huc = (HttpsURLConnection) url.openConnection();//设置参数//设置请求方式huc.setRequestMethod("GET");//允许使用输入流huc.setDoInput(true);//允许使用输出流huc.setDoOutput(true);//设置连接超时时间huc.setConnectTimeout(5200);//设置读取超时时间huc.setReadTimeout(5000);//获取响应状态码int responseCode = huc.getResponseCode();if (responseCode == HttpsURLConnection.HTTP_OK) {InputStream is = huc.getInputStream();FileOutputStream fos = new FileOutputStream("冲击的力量.jpg");byte[] b = new byte[1024];int len;while ((len = is.read(b)) != -1) {fos.write(b, 0, len);}is.close();fos.close();}else if (responseCode == HttpsURLConnection.HTTP_NOT_FOUND) {System.out.println("报错了 --- 页面未找到");}}}